Pump-motor units are used, particularly in the motor vehicle field, for feeding of hydraulic fluids, particularly of lubricating oil or fuel. A rotor of the pump, which conveys the fluid from the tank and compresses it, is driven by a motor, usually an electric motor. A shaft of the electric motor is connected to a rotor of the pump, in order to drive the pump. For this purpose, generally the shaft of the electric motor is rotatably journaled, by means of a bearing arrangement, in the electric motor. A pump shaft of the pump, which is securely connected to the rotor of the pump, is rotationally journaled in the pump with the help of a further bearing arrangement. To connect the shaft to the pump shaft, a coupling is provided.
Thus, conventional pump-motor units have at least two bearing arrangements, as well as a coupling, leading to high development and manufacturing costs. Further, a configuration with multiple bearing arrangements means that one must reckon with elevated frictional losses, since each bearing position of the bearing arrangement creates a respective frictional loss. Higher frictional losses, in turn, necessitate an increase of the required motor capacity of the electric motor, for any given pump capacity.